radionuclide studies in renovascular hypertension (rvh) in
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Radionuclide Studies in Renovascular Hypertension (RVH)
in Paediatric Population
Isabel RocaHU VALL HEBRONBarcelona, Spain
basal captopril
basal captopril
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Method Pros Cons
Doppler ultrasound• Reasonable cost• Wide availability• No ionizing radiation
• Operator-dependent• Many non-diagnostic studies
Angio MRI• Useful to separate responders from non-responders• No ionizing radiation
• Low resolution (small vessels)• Motion artifacts, stents
Captopril MRI• No nephrotoxic contrast media• Pacient with renal failure• No ionizing radiation
• High cost• Limited availability• Low PPV
Renovascular HypertensionImaging Studies
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Method Pros Cons
Angio CT
• High spatial resolution• Shows calcium content• No stent artifacts• Measures cortical thickness and renal size
• Nephrotoxic contrast media• High dosimetry• Ppoor visualization small vessels
Captopril Renography
• Reasonable cost• Identifies responders• High NPV
• Low resolution (small vessels)• Motion artifacts, stents
Renal Angiography• “Gold standard” for renal artery stenosis• Less contrast volume if digital subtraction is used
• Nephrotoxic contrast media• High dosimetry• Interobserver variability
Renovascular HypertensionImaging Studies
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Renovascular HypertensionPathophysiology
Reduced perfusion of affected kidney
Renin-angiotensin system is activated
Releasing:- angiotensin II
vasoconstriction- aldosterone
plasma expansion
Renal artery stenosis
Attempting to preserve / increase renal blood
pressure
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DETECTED THROUGH FUNCTIONAL STUDIES
FUNCTIONAL DETERIORATIONof stenotic kidney
PHARMACOLOGICBLOCKADE
of activated renin-angiotensin system
REVERSIBILITY
• greater in initial phase• predicts a good response to revascularization
• Renogram: MORPHO-FUNCTIONAL• Information on reversibility ofarterial lesion
Renovascular HypertensionPathophysiology
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NON-REVERSIBLEHIPERTENSION
AFTER REVASCULARIZATION(DILATION OF STENOTIC
ARTERY)
Hipertensión renovascularFase crónica
“FIXED”HIPERTENSION
PHARMACOLOGIC BLOCKADE
less effective
Renovascular HypertensionChronic Phase
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Renal Angiography
-“Gold standard ” for diagnosis of RVH.- Detects anatomic changes in renal arteries.- Does not inform about:
- functional changes - reversibility of the lesion
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en caso de HTA con estenosis reversible de la arter ia renal• disminución del filtrado glomerular del riñón afecto y • aumento del tiempo de tránsito renal del trazador
- Well standardized technique- Neds comparison of :
- basal vs.- post-captopril renography
CAPTOPRIL:- disminuyendo la VC de la arteriola eferente post-glomerular- evita la conversión de angiotensina I a angiotensina II
basal captopril
Captopril Renography
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• withdraw ACE inhibitors � 5-7 days before the study
• temporarily suspend diuretics • temporarily suspend calcium channel blockers
• The technique is applicable to patients� with one kidney� with renal transplantationBut a captopril dose adjustment is needed
Captopril RenographyPatient Preparation
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PREPARATION• Hydration
• Micturition
• 0.25 mg /kg furosemide intravenous at minutes 0 (to avoid ectasia in excretory pathways)
• Withdraw ACE inhibitors• Withdraw, if possible, diuretics and calcium blockers
Captopril RenographyTechnique
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CAPTOPRIL
� Administration of captopril orally (or intravenously) 60 minutes before the study
� Typical dose:� 50 mg adults - 25 mg in single kidney� dose weight adjusted
� BP and HR monitoring: at least 2 determinations � Before administration of captopril� before the start of the renogram
Captopril RenographyTechnique
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LIMITATIONS• Low or very low function of affected kidney • Transient decrease in glomerular filtration rate secondary to
� Intravenous injection of contrast (CT angiography)� On the preceding 2 weeks� Both ionic and non-ionic contrast
RADIOPHARMACEUTICALS AND TECHNIQUE• Adults and children
� DTPA or MAG3 renogram• Infants and young children and in cases of suspected pathology of a polar artery
� DMSA renal scan
Captopril RenographyTechnique
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123I-OIH
99mTc-EC
99mTc-MAG3
123I-OIH
99mTc-DMSA99mTc-GH
99mTc-DTPA
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RENOGRAM99mTc-DTPA99mTc-MAG3
• ↓ function• ↑ transit time• cortical tracer retention
CORTICAL SCINTIGRAPHY99mTc-DMSA
• ↓ function� diffuse� focal
Captopril RenographyInterpretation: Basal vs. Captopril comparison
basal captopril
Positive findings:
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RENOGRAM • RK• LK
� preserved function and excretion bilaterally post-captopril
RENOGRAM• RK• LK
� Functional drop inferior half LK post-captopril
basal captopril
basal captopril
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CAPTOPRIL RENOGRAM• RK• LK: focal area with prolonged transit time
BASAL RENOGRAM • RK• LK
� preserved function and excretion bilaterally post-captopril
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Digital subtracton angiography:• Multiple small aneurysms associated with irregularities of medial and inferior polar arteries.• Focal stenosis >70% subsegmental artery.
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basal
captopril
Left renal artery stenosis
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Renal cortical scintigraphy with 99mTc-DMSA • Focal reduced uptake • Polar artery stenosis
basal captopril
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basal captopril
ANGIOGRAPHY
normal abnormal
DMSA(basal)
normal 4 4
abnormal 5 7
DRF<45% or focal defect
SENSITIVITY 64%
SPECIFICITY 44%
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basal captopril
ANGIOGRAPHY
normal abnormal
DMSA(captopril)
normal 4 1
abnormal 4 10
SENSITIVITY 91%
SPECIFICITY 50%
DRF<45% or focal defect
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RENOGRAM:LK functional cancellation
ANGIOGRAPHY:Left renal artery stenosis
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ANGIOGRAPHY• RA stenosisCAPTOPRIL RENOGRAPHY
• Chronic renal failure• Right K = 10%
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basal captopril
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basal captopril
RENAL TRASPLANT • max 25 mg captopril• captopril:
• ↓↓↓↓ function• ↑↑↑↑ transit time• ↓↓↓↓ excretion
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Renovascular disease
Radionuclide Renography• basal• captopril
99MTc-DTPA
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Basal
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Captopril
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Post revascularization
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45%55%
46%54%
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44%56%
37%63%
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32%68%
22%78%
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Captopril renography is a morpho-functional technique
envolving low irradiation which gives information about
renovascular lesions as well as an estimation of potential
lesion reversibility, predicting treatment response.
Captopril RenographyConclusion
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